A beam splitter is an optical device that splits a beam of light into two separate beams of light. Often, beam splitters are used to divide light into two beams that each comprises same information. Sometimes, however, it is useful to separate a beam into two separate and different beams of light based on an identifiable parameter.
Polarising beam splitters divide a beam of light based on a polarisation component thereof. For example, a Wollaston prism uses birefringent materials, for splitting light into constituent portions—separate optical signals—of differing polarisation.
Using a polarisation beam splitter and combiner allows, for example, for polarisation modulation of optical signals. Signals provided from traditional polarisation beam splitters have different polarisations and are therefore ill suited to being efficiently coupled into a same waveguide.
It would be advantageous to provide a beam splitter that supports polarisation beam splitting and rotation for coupling to a waveguide.